Dell U2723QE with 2019 Macbook Pro

A note on "full resolution":

You can run in "More Space" mode, with no Retina scaling, but it's not very usable. Text and objects get very tiny, because you're trying to crowd 2.25x as much "stuff" as fits on a 27" 2.5K monitor into the same physical amount of space. It would be like printing a book in 4-point text, just because commercial book publishing equipment has enough resolution that you could.

System Information (Option- / System Information…) -> Graphics/Displays

DELL U2723QE:

  Resolution: 3840 x 2160 (2160p/4K UHD 1 - Ultra High Definition)

  UI Looks like: 3840 x 2160 @ 60.00Hz

  Main Display: Yes

  Mirror: Off

  Online: Yes

  Rotation: Supported

I have that same monitor and am running it in Retina "like 2560x1440" mode. The Mac draws on a 5K canvas, then downscales things to fit on the 4K monitor. The monitor reports that it is getting a 4K signal. The system uses the full resolution of the monitor – not to cram more stuff onto the screen until it becomes unreadable, but to draw text and fill in photo areas in finer detail.

System Information (Option- / System Information…) -> Graphics/Displays

DELL U2723QE:

  Resolution: 5120 x 2880 (5K/UHD+ - Ultra High Definition Plus)

  UI Looks like: 2560 x 1440 @ 60.00Hz

  Main Display: Yes

  Mirror: Off

  Online: Yes

  Rotation: Supported

There are Retina "like 3008x1692" and "like 3360x1890" modes, but I don't know if they would be available on your Mac. They would involve pixel-doubled canvas resolutions greater than 5K, and I don't believe that any of the 2019 MacBook Pros supported monitors with resolutions greater than 5K.

You didn't say which 2019 MacBook Pro you have. But it looks like all of them support UHD 4K (3840x2160 pixel) displays, so I believe it should work.

MacBook Pro (13-inch, 2019, Two Thunderbolt 3 ports) - Technical Specifications

MacBook Pro (13-inch, 2019, Four Thunderbolt 3 ports) - Technical Specifications

MacBook Pro (16-inch, 2019) - Technical Specifications

https://www.dell.com/en-us/shop/dell-ultrasharp-27-4k-usb-c-hub-monitor-u2723qe/apd/210-bdpf/monitors-monitor-accessories

Grant Bennet-Alder wrote:

DisaplayPort (over USB or direct) can use HBR2 transmission mode at 17.28 G bits sec to attain 4K at about 75 Hz, if everything else supports that, otherwise call it 4K at 60 Hz. it can attain 5K, but only at 30 Hz refresh.

To go higher, it needs to step up to HBR3, which requires 25.92 G bits/sec, higher than the nominal 20 G Bits/sec attainable on USB 3.2 so it needs more data conductors -- like Thunderbolt port, cable, and display input can provide.

I did not give daisy-chaining a moment's thought, it can't make 5K over USB cables.

In some Retina modes, the internal canvas might be 5K – 6K. I think that the GPU must be downscaling this before transmission. No matter which Displays Setting mode (from Larger Text to More Space) I select, the monitor reports receiving 3840x2160, 30-bit, 60 Hz input.

layoutpad wrote:

Want to Dell U2723QE as second Monitor. (Main monitor for photoshop work).

Will use Dell USB-C to USB-C cable

Don't count on the daisy-chaining feature that Dell talks about. Instead,

1. Plug the U2723QE into one of your MBP's USB-C ports, connecting the other monitor through another, or
2. Plug both monitors into a Thunderbolt dock.

How crisp is the resolution/color at 2560 x 1440 @ 60.00Hz?

Pretty good. I don't think it's quite as crisp as that of a 27" 5K Retina iMac, or a 27" Apple 5K Studio Display, but Apple discontinued the former, and priced the latter very high by 27" 5K Retina iMac standards.

And is the set-up plug n' play, or are there any tips you can offer me?

It was plug and play. There's a "Dell Display and Peripheral Manager for macOS" application, but I didn't install it. Looks like it lets you control brightness/contrast from the Mac, configure picture-in-picture, etc. You can set the brightness/contrast using controls on the monitor without installing the Dell software.

The "quick start" sheet that came in the box (second link below) is pretty spartan, so you may want to look at the online user guide before setting up the monitor.

https://www.dell.com/support/home/en-us/product-support/product/u2723qe-monitor/docs

https://dl.dell.com/content/manual14307322-dell-u2723qe-monitor-quick-start-guide.pdf?language=en-us

https://dl.dell.com/content/manual12109242-dell-u2723qe-monitor-user-s-guide.pdf?language=en-us

DisaplayPort (over USB or direct) can use HBR2 transmission mode at 17.28 G bits sec to attain 4K at about 75 Hz, if everything else supports that, otherwise call it 4K at 60 Hz. it can attain 5K, but only at 30 Hz refresh.

To go higher, it needs to step up to HBR3, which requires 25.92 G bits/sec, higher than the nominal 20 G Bits/sec attainable on USB 3.2 so it needs more data conductors -- like Thunderbolt port, cable, and display input can provide.

I did not give daisy-chaining a moment's thought, it can't make 5K over USB cables.

<< Will use Dell USB-C to USB-C cable . >>

not with that cable you won't.

USB-C cable does not have enough bandwidth to go higher than 5K resolution at higher than 30 Hz.

You need a genuine ThunderBolt cable and it needs to be no longer than 0.8 meters for Apple brand, 0.5 meters for Brand-X.

Thunderbolt has twice the data pathways as USB-C.

Grant Bennet-Alder wrote:

<< Will use Dell USB-C to USB-C cable . >>

not with that cable you won't.

USB-C cable does not have enough bandwidth to go higher than 5K resolution at higher than 30 Hz.

You need a genuine ThunderBolt cable and it needs to be no longer than 0.8 meters for Apple brand, 0.5 meters for Brand-X.

Thunderbolt has twice the data pathways as USB-C.

Is your concern that the OP will try to attach the U2723QE and an existing non-Thunderbolt monitor via the same Mac USB-C host port, without the use of a Thunderbolt dock? I don't think the Mac supports daisy-chaining two monitors via a USB-C (DisplayPort) (NON-Thunderbolt) connection.

So when Dell says that

"U2723QE is the world’s first 27" 4K monitor which allows daisy chaining of an additional 4K monitor at full resolution via USB-C—enabled by Display Stream Compression (DSC)."

the OP should not rely on Macs supporting this feature of that monitor.

That leaves two options:

1. The OP could get a Thunderbolt dock that can drive two non-Thunderbolt monitors. This would let the OP have a single docking cable – the one to the Thunderbolt dock.
2. The OP could connect the monitors to different Mac host ports. In this case, docking would involve connecting at least two cables, but would not require Thunderbolt.

I don't have two monitors, but I do have that same Dell 4K monitor plugged into my M1 Max Mac Studio, using the USB-C to USB-C cable which came in the box. There's a USB audio card, a USB microphone, and a wall-powered CD/DVD drive hanging off the hub ports on the monitor. I haven't tested any CD/DVD activity more data-intensive than playing an audio CD yet, but so far, the whole thing works like a charm.

Grant Bennet-Alder wrote:

<<. 30-bit >>

WAIT. That's 10 bits per pixel color. Most users don't use that unless they are doing glossy magazine-cover work.

I'm not doing that type of work – but it appears that the monitor is capable of receiving a 10-bit-per-pixel signal and the Mac Studio is willing to send it. I think they negotiated this all by themselves, without my help.

at 10 bits/pixel, you need to use a different chart, and it shows you can't quite make 5K at 60 Hz, but it can make 50 Hz.

It's not a 5K monitor. It's a 4K monitor. When you use Retina "like 2560x1440" mode, the Mac uses an internal canvas with a 5K resolution, but the monitor reports receiving a 4K signal.

I would assume that the downsampling takes place in the GPU before the signal is sent out over USB-C. I don't think the monitor would know what to do with a 5K signal even if the USB-C connection could carry one.

<<. 30-bit >>

WAIT. That's 10 bits per pixel color. Most users don't use that unless they are doing glossy magazine-cover work.

at 10 bits/pixel, you need to use a different chart, and it shows you can't quite make 5K at 60 Hz, but it can make 50 Hz.

https://en.wikipedia.org/wiki/DisplayPort#Refresh_frequency_limits_for_HDR_video

the other 'can of worms' is that ThunderBolt as implemented in some Macs does not quite have enough data transfer ability to hit the next transmission mode, which needs 38.69 G bits/sec. The nominal 40 G bits/sec ThunderBolt is actually supported by about a 32 G bits/sec data channel from the Mac.

OWC generally knows what they are talking about, so their 0.7 meter cable should be good to go.

Let Readers know about your experience!

so sorry, I though you wanted to drive your (5K capable) display at 10 bits/pixel at 5K.

<< I would assume that the downsampling takes place in the GPU before the signal is sent out over USB-C. >>

that is how its supposed to work, buy Apple has not made detailed easily-accessible technical descriptions available. The display gets bit-for-bit what needs to be displayed, after all adjustments have been made inside the Mac.

My understanding of how this works is that graphics are always displayed at full native resolution of the display. (otherwise you are discarding information the user may have worked really hard to obtain.)

Only the elements of the User Interface -- TEXT (and associated User interface elements) has scaling applied to make its size manageable without losing fine lines and sharp edges.

I guess I have never been too worried about text size on a 5K vs 4K -- and whether that would appear the same size on screen, so I have not 'done the math' to figure it all out.